1. Field of the Invention
The invention relates to a reticle, particularly to a reticle used for obtaining both semiconductor dice as products and TEG (Test Element Group) dice. The invention also relates to a semiconductor die obtained with the reticle and a method of manufacturing a semiconductor device with the reticle.
2. Description of the Related Art
In an exposure process for transferring a desired pattern onto a semiconductor wafer, a photomask called a reticle is generally used. A reticle formed with a pattern which is about four or five times larger than an actual pattern is used in a stepper (a reduction projection exposure system), and through this reticle ultraviolet light or excimer laser light is applied to a semiconductor wafer to transfer a reduced desired pattern thereon.
Some reticles are provided with TEG (Test Element Group) die pattern regions as well as semiconductor die pattern regions as actual products. A TEG die is a sample for evaluating the element structures, property, electric property, circuit operation, reliability and yield of products (semiconductor dice).
A conventional reticle having semiconductor die pattern regions and TEG die pattern regions will be described referring to figures. FIG. 3 is a schematic plan view of a conventional reticle 100.
This reticle 100 provides six semiconductor dice at one shot. A substrate 101 made of quartz is formed with six semiconductor die pattern regions 102 which are to be actual products and two TEG die pattern regions 103 placing the semiconductor die pattern regions 102 therebetween. The semiconductor die pattern regions 102 and the TEG die pattern regions 103 have the same shapes (almost rectangular shapes) in a plan view and the same sizes.
Dicing line regions 104 are formed between the adjacent semiconductor die pattern regions 102 and between the semiconductor die pattern regions 102 and the TEG die pattern regions 103.
TEG patterns transferred onto a semiconductor wafer with this reticle 100 are used for evaluating the property of the semiconductor dice on the wafer and not needed after the evaluation. Therefore, the TEG dice are cut out in a dicing process as well as the semiconductor dice, and removed. The relevant technique is described in Japanese Patent Application Publication No. 2005-283609, for example.
For obtaining semiconductor dice as products as many as possible from the limited area of a semiconductor wafer, there has been an increasing demand for minimizing the area of the TEG dice.
With the described conventional reticle, however, the area of the two TEG die pattern regions 103 which are not needed eventually makes the yield of the semiconductor dice low. Although it is possible to form only one TEG die pattern region 103 on the reticle to increase the yield, this causes reduction of the reliability of semiconductor dice as products since elements are not sufficiently evaluated.
Alternatively, it is also proposed that TEG die patterns are formed in dicing line regions on a semiconductor wafer instead of surrounding the TEG dice by the dicing line regions 104 as described above. However, this causes various metal materials (e.g. aluminum wiring or an electrode) formed in the TEG dice to scatter by contact of a blade in a dicing process, and the scattering metal materials are likely to adhere semiconductor dice. This also causes a problem of reducing the reliability and yield of these semiconductor dice. Furthermore, when metal pieces are left in the dicing line regions, the yields of some products may be reduced when the semiconductor die is mounted on a circuit board or the like.
The invention is directed to providing a reticle that realizes sufficient evaluation of elements with TEG dice and increases the number of semiconductor dice obtained from one semiconductor wafer. Furthermore, the invention is directed to enhancing the reliability and yield of the semiconductor dice.